Multi-Fiber Ferrule with Improved Eye Safety

ABSTRACT

A multi-fiber ferrule has lenses that have different prescriptions to disperse the light emitted from the multi-fiber ferrule. Alternatively, the lens for each individual optical fiber can be moved relative to the optical fiber or the optical fiber opening in the multi-fiber ferrule to cause the laser beam exiting the multi-fiber ferrule to be redirected into a structure that absorbs or blocks the laser.

REFERENCE TO RELATED CASE

This application claims priority under 35 U.S.C. § 119 (e) toprovisional application No. 62/165,768 filed on May 22, 2015, thecontents of which are hereby incorporated by reference in theirentirety.

BACKGROUND OF THE INVENTION Field of the Invention

The current Prizm® MT ferrule produced by Applicant US Conec uses ahighly collimated laser beam. The laser beam is approximately 180microns in diameter. The current Prizm MT ferrule contains up to 64fibers in one multi-fiber ferrule. The collimated beam, the small sizeof the collimated beam and the number of fibers present a number ofconcerns regarding eye safety.

There two eye safety standards from the International ElectrotechnicalCommission (IEC). The first is 60825-1, which is for the classificationof a laser product. The second is 60825-2, used to determine the hazardlevel from an optical fiber communication system during the event suchas a fiber break. The most stringent condition of the 2 standards shouldapply to determine the radiation hazard and human safety.

In order to comply with these standards, the fiber optic industry hassometimes used mechanical shutters to either block the collimated ordiverging laser beams exiting the multi-fiber ferrule to mitigate therisk to a user's eye. The mechanical shutters add cost and requireadditional space in an already very small space. Sometimes electricalshutters are also used to prevent a significant amount of light fromexiting from the connector unless both ends are plugged in. Instead ofusing either electrical or mechanical shutters, the present inventionresolved the eye safety concerns optically, using the features of themulti-fiber ferrule to prevent the collimated laser beam from entering aperson's eyes or at least reducing the amount of light that can possiblyenter the light at any given time.

SUMMARY OF THE INVENTION

The present invention is directed to a multi-fiber ferrule that includesa unitary main body having a front end, a back end, and a middle portiondisposed between the front end and back end, first opening adjacent theback end of the unitary main body, the first opening configured toreceive at least two optical fibers, a plurality of optical fiberopenings extending from the first opening toward the front end, each ofthe plurality of optical fiber openings configured to receive an opticalfiber, and a plurality of lenses disposed adjacent the front end in atleast one rows and a plurality of columns, each of the plurality oflenses being in optical alignment with a respective one of the opticalfiber openings, the lenses in each column having a differentprescription from the lenses in each adjacent column.

In some embodiments, the columns of lenses comprise a first plurality ofcolumns and a second plurality of columns, the lenses in the firstplurality of columns have a first prescription and the lenses in thesecond plurality of columns having a second prescription.

According to another aspect of the present invention, a multi-fiberferrule includes a unitary main body having a front end, a back end, anda middle portion disposed between the front end and back end, a firstopening adjacent the back end of the unitary main body, the firstopening configured to receive at least two optical fibers, a pluralityof optical fiber openings extending from the first opening toward thefront end, each of the plurality of optical fiber openings configured toreceive an optical fiber and having an opening axis extendinglongitudinally therethrough, and a plurality of lenses disposed adjacentthe front end, each of the plurality of lenses being in opticalalignment with a respective one of the optical fiber openings, each ofthe plurality of lenses having an optical axis, the optical axis of eachof the plurality of lenses being parallel to but offset from the openingaxis of a respective optical fiber opening.

In some embodiments, the light passing through each of the plurality oflenses from an optical fiber disposed within the optical fiber openingsexits the plurality of lenses at an angle of between 10 and 30 degreesrelative to the opening and optical axes.

In other embodiments, the multi-fiber ferrule has a longitudinal axisextending therethrough between the front and back end and the lightpassing through each of the plurality of lenses from an optical fiberdisposed within the optical fiber openings exits the plurality of lensesat an angle of at least 3.6 degrees radially outward relative to thelongitudinal axis of the multi-fiber ferrule.

According to yet another aspect of the present invention, a fiber opticconnector includes a connector housing having a front end, a back end,an inside surface extending between the front and back ends defining anopening in the connector housing, a multi-fiber ferrule configured to beinserted into the opening of the connector housing, the multi-fiberferrule including a unitary main body having a front end, a back end,and a middle portion disposed between the front end and back end, afirst opening adjacent the back end of the unitary main body, the firstopening configured to receive at least two optical fibers, a pluralityof optical fiber openings extending from the first opening toward thefront end, each of the plurality of optical fiber openings configured toreceive an optical fiber and having an opening axis extendinglongitudinally therethrough, and a plurality of lenses disposed adjacentthe front end, each of the plurality of lenses being in opticalalignment with a respective one of the optical fiber openings, each ofthe plurality of lenses having an optical axis, the optical axis of eachof the plurality of lenses being parallel to but offset from the openingaxis of a respective optical fiber opening such that light passingthrough each of the plurality of lenses from an optical fiber disposedwithin the optical fiber openings exits the plurality of lenses directedto the inside surface of the connector housing.

In some embodiments, the fiber optic connector also includes lightabsorbing material attached within the opening of the connector housingbetween the front end of the connector housing and the front end of themulti-fiber ferrule.

It is to be understood that both the foregoing general description andthe following detailed description of the present embodiments of theinvention are intended to provide an overview or framework forunderstanding the nature and character of the invention as it isclaimed. The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated into and constitutea part of this specification. The drawings illustrate variousembodiments of the invention and, together with the description, serveto explain the principles and operations of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is schematic diagram of a multi-fiber ferrule with an eye at oneof the two distances used in measuring the laser beam hazard;

FIG. 2 is a front perspective view of a lensed standard multi-fiberferrule with 64 fibers and lenses;

FIG. 3 is a schematic diagram of the effect of the lenses on the laserbeam leaving one multi-fiber ferrule and entering another;

FIG. 4 is a schematic diagram of a lens in a standard multi-fiberferrule on the right and a weaker lens (larger radius of curvature) in amating multi-fiber ferrule on the left which causes the beam to divergeas it exits the lens;

FIG. 5 is a schematic diagram of one lens in a standard multi-fiberferrule on the right and a flat lens (smaller power) in a matingmulti-fiber ferrule on the left, also causing divergence of the beam;

FIG. 6 is a schematic diagram of a lens in a standard multi-fiberferrule on the right and a concave lens in a mating multi-fiber ferruleon the left;

FIG. 7 is illustrates one embodiment of a multi-fiber ferrule using thedifferent lens prescriptions to reduce the number of collimated beamsthat exit the multi-fiber ferrule;

FIG. 8 is a schematic diagram of an optical fiber offset from an opticalaxis on a lens in a multi-fiber ferrule according to another embodimentof the present invention;

FIG. 9 is a schematic diagram of a launching lens and a receiving lenswith the offset optical fibers from FIG. 8 in two mated multi-fiberferrules;

FIG. 10 is a front right perspective view of a fiber optic connectorwith a multi-fiber ferrule having offset optical fibers relative to thelenses and directing the beam into the connector;

FIG. 11 is a top perspective view of a receptacle that has the fiberoptic connector of FIG. 10 installed therein, the multi-fiber ferrulebeing recessed within the receptacle;

FIG. 12 is a front view of the receptacle of FIG. 11, illustrating themulti-fiber ferrule inserted into the receptacle and the light absorbingmaterial in the receptacle;

FIG. 13 is a top perspective view of two MTP connectors using the lightabsorbing material along with MT multi-fiber ferrules having lensesoffset from the optical fiber axis and directed into absorbing materialon the inner housings thereof;

FIG. 14 is a front perspective view of another multi-fiber ferruleaccording to the present invention that requires only one themulti-fiber ferrule be molded;

FIG. 15 is a schematic illustrating the alignment of the current lensdesign at 70 mm in a 7 mm area;

FIG. 16 is an illustration of the beams from a multi-fiber ferrule withan offset causing as little as a 3.6 degree redirection of the laserbeam to eliminate about 75% of the laser beams that could be in the 7 mmarea; and

FIG. 17 is a schematic of the lens and optical fiber alignment toachieve the redirection of the laser beams in FIG. 16.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the present preferredembodiment(s) of the invention, examples of which are illustrated in theaccompanying drawings. Whenever possible, the same reference numeralswill be used throughout the drawings to refer to the same or like parts.

Referring to FIG. 1, in order to understand the reasons for the presentinvention, a diagram that presents a visualization of how measurementsare taken under the current eye safety standards, a multi-fiber ferrule100 is illustrated. The multi-fiber ferrule 100 maybe any multi-fiberferrule, including a ferrule according to the present invention asdisclosed herein. The details of a multi-fiber ferrule using lenses atthe front end can be found in applicant's co-pending application Ser.No. 14/211,480, the contents of which are incorporated herein byreference. As a brief description of the multi-fiber ferrule 100, theunitary body preferably has an front end 102, a back end 104, and amiddle portion 106 disposed between the front end 102 and the back end104. The multi-fiber ferrule 100 is a preferably a unitary ferrule, thatis, a single integral element that is preferably molded at the same timefrom a homogeneous material. The multi-fiber ferrule 100 has a firstopening 108 adjacent the back end 104 to receive optical fibers therein.The multi-fiber ferrule 100 may also have an opening 120 from the topsurface 122 of the multi-fiber ferrule 100 that is in communication withthe first opening 108 to inject epoxy to secure optical fibers withinthe multi-fiber ferrule 100. A plurality of micro-holes 124 extendthrough the middle portion 106 to hold and position optical fibersinserted into the first opening 108. The micro-holes 124 are preferablychamfered.

The front end 102 has a recessed portion 130 with a plurality of lenses132 visible therein. The plurality of lenses 132 are preferably set backfrom the front face 134 of the front end 102 and are preciselypositioned to be in optical alignment with the plurality of micro-holes124 (and the optical fibers inserted therein). Preferably, the number oflenses 132 corresponds to and are in individual alignment with thenumber and position of the micro-holes 124. The plurality of lenses 132are molded with the rest of the optical ferrule 100 and are generally acollimating-type lens. That is, the lenses 132, because they are incontact with air in the recessed portion 130, are collimating due to thedifference in the index of refraction between the polymer and the airand the shape of the lens. The light exiting from the optical fibersinserted into the multi-fiber ferrule 100 passes through the lenses 132and is then collimated into a near-parallel light beam to be received bylenses of an identical, mated multi-fiber ferrule, which then focus thereceived light onto the ends of the optical fibers in that multi-fiberferrule. It is anticipated that the front face 134 of the multi-fiberferrule 100 makes physical contact with the front face of anothermulti-fiber ferrule.

When determining if a particular device meets the requirements for eyesafety, measurements of the light are taken 70 mm away from the frontface 134 fiber-optic ferrule. Since the pupil in a human eye 140 isabout 7 mm in diameter, the light entering a 7 mm aperture at 70 mm fromthe front of the multi-fiber ferrule is measured. This generallyapproximates the amount of light that would be entering the human eye.The present invention is directed to a multi-fiber ferrule that reducesthe amount of light that can reach the eye.

FIG. 2 is front view of the multi-fiber ferrule 100. The multi-fiberferrule 100 accommodates up to 64 optical fibers (not shown). The endsof the optical fibers are disposed within the multi-fiber ferrule 100,each positioned behind one of the lenses 132, the lenses 132 beingexposed at the front end 102 of the multi-fiber ferrule 100. The lenses132 each have a prescription that causes the light exiting from themulti-fiber ferrule 100 to be collimated and exiting at a perpendicularangle to the front face 134 of the multi-fiber ferrule 100.

As illustrated in FIG. 3, which schematically represents two lenses 132in two mated multi-fiber ferrules, the lenses 132 are shaped to allowthe light L to be collimated as it exits the multi-fiber ferrule 100 (orfocuses the light on the end of the optical fiber 116 for the receivinglens). In this manner, the multi-fiber ferrules are bidirectional,allowing the light path to be either right-to-left or right-to-left inFIG. 3.

Returning to FIG. 2, the multi-fiber ferrule 100 may have an integrallymolded guide post 136 on one side and a guide post opening 138 on theother side. When two multi-fiber ferrules 100 are mated to one another,the guidepost 136 of one of the multi-fiber ferrules 100 aligns withguide post opening 138. Thus, the multi-fiber ferrules 100 are matedwith the top surfaces 122 aligned with one another. As can be realized,if the second multi-fiber ferrule was not present, the collimated lightwould be able to travel a long distance. Given that the 16 lenses oneach row extend about 4 mm across, they will certainly be containedwithin the 7 mm aperture discussed above. As a result, it would bepreferable to block the light, spread it out so it is not so intense, ordirect the light so that it does not travel straight out of themulti-fiber ferrule 100. However, each of these solutions interfereswith the mating of the multi-fiber ferrules and maintaining anacceptable insertion loss across the mating junction.

Illustrated in FIG. 4 is a left lens 150 that has a weaker prescriptionthan the right lens 152. The right lens 152 has a smaller radius ofcurvature (ROC) and a stronger prescription than of lens 132 and theleft lens 150 has a ROC that is larger than lens 132. In this way, thelight exiting the lens 150 will be more spread out than the lightleaving lens 152. If the light leaving lens 150 is diverging as itleaves the multi-fiber ferrule 100, then the intensity at 70 mm isdramatically reduced from the collimated beam exiting lens 132. Further,if the light exiting lens 152 unblocked, then the rays will cross anddiverge before the 70 mm distance is reached. However, aligning themulti-fiber ferrule with the lens 150 having a larger ROC will require amore exact (a tighter) alignment with a multi-fiber ferrule having thelens 152 than the mating illustrated in FIG. 3. The multi-fiber ferrulepair illustrated in FIG. 4 will still be bi-directional. With the twodifferent prescriptions, it will be necessary to have two separatemulti-fiber ferrules—one with lenses 152 and one with lenses 150 (notpreferred) or the lenses of the multi-fiber ferrule will have to beplaced so that when the multi-fiber ferrules are mated, thecorresponding lenses are matched. This arrangement is discussed below inmore detail.

In another embodiment in FIG. 5, a lens 160 is matched with a lens 162.The lens 160 is a flat lens, having an essentially infinite ROC. In thiscase, all of the prescription power is in lens 162. Lens 160 causes thelight L to diverge to an even greater degree than lens 150 discussedabove. This divergence of the light L reduces even further thepossibility of intense light entering an eye. Due to the increase indivergence of the light L, the alignment must be still greater than thatof the lenses in FIGS. 3 and 4.

In yet another embodiment in FIG. 6, a lens 170 is matched with a lens172. The lens 170 is a concave lens, causing even more divergence of thelight L. With the greatest amount of divergence of the light L of thelenses disclosed above, the alignment of the two lenses illustrated inFIG. 6 is most critical.

FIG. 7 illustrates the front face of a multi-fiber ferrule 180 using thelenses discussed above. Since the object is to manufacture only onemulti-fiber ferrule 180 for the technicians in the lab or factory (oreven the technicians in the field) that can be used on both sides, thetwo multi-fiber ferrules 180 need to match when they aligned and matedas discussed above: top surfaces are on the same side of the mated pair.However, in order to be able to so mate the multi-fiber ferrules, thelenses having one prescription in the multi-fiber ferrule 180 need to bearranged so that they are aligned with lenses having anotherprescription. One arrangement would be to alternate the prescription inthe columns of the lenses. For example, the odd columns (looking fromthe front towards the back of the multi-fiber ferrule (as illustrated inFIG. 7) are (from left to right) the first, third, fifth, etc. columnsand would have a first prescription (that of lenses 132 for example) andthen the even columns would have a different prescription (e.g., that inlenses 150, 160, 170). When two such ferrules are mated, then the lenseswould be mated with a corresponding prescription as noted above. Thiswould reduce the light reaching the 7 mm aperture at 70 mm and protectthe user's eyes.

Another approach to affecting the beam of light exiting from amulti-fiber ferrule is illustrated in FIGS. 8-11. FIG. 8 schematicallyillustrates a lens 200 that is optically off-centered from an opticalfiber 202. The lens 200 has an optical axis A-A, noting that the lenshas a spherical outer surface 204. However, the lens 200 may also beaspherical or biconic to achieve the same effect. The optical fiber 202has a fiber axis B-B that is normally aligned with the optical axis ofthe lens 200. See, e.g., FIGS. 3-6. It should be noted that the fiberaxis B-B also corresponds to an axis of the micro-holes (or opticalfiber openings) 124. As is known in the art, the micro-holes 124 areonly slightly larger than the optical fibers making the longitudinalaxis of each of the micro-holes co-axial with the fiber axis B-B thatare inserted into the multi-fiber ferrules. The distance of offset Ddetermines the angle ∝ at which the beam 206 exits from the lens 200relative to the optical axis A-A. Preferably, the angle ∝ is between 10and 30°. Alternatively, the shape of the lenses could be designed with anon-radially symmetric form, whereby the light would exit at an anglerelative to the axis of the fiber. With the beam 206 exiting at an angle∝, the beam 206 is directly into a structure associated with multi-fiberferrule, i.e., a connector housing, adapter, etc. For example, asillustrated in FIG. 10, there is a connector housing 210 (also referredto as a plug) that accepts a multi-fiber ferrule 212 with the lenses200. The connector housing 210 could be, as one embodiment, the MXCdesign supplied by applicant, US Conec. Because the multi-fiber ferruleis in a recessed position (does not extend outside the connectorhousing), a light absorbing material 216 could be disposed on an insidesurface 214 of connector housing 210. The light absorbing material 216could be a black flock cloth or other light absorbing material.Alternatively, the inside surface 214 of the connector housing 210 cansimply be a dark, but non-reflecting surface.

FIG. 9 illustrates how lens 200 mates with a lens 220 from a multi-fiberferrule on the other side. The lens 220 has an optical axis C-C that isoffset by a distance E from the optical axis A-A of lens 200. The lens220 is also offset from the fiber axis D-D (or the optical fiber openingin a corresponding multi-fiber ferrule). This arrangement also allowsthe multi-fiber ferrules to be bi-directional.

The connector housing 210 is inserted into the receptacle 230illustrated in FIG. 11. The connector housing 210 is inserted into thereceptacle 230 from the right side. Since the multi-fiber ferrule 212 isrecess relative to the connector housing 210, which is also recessedrelative to the receptacle 230, the light absorbing material 216 couldalso be dispose on the inside surface 232 of the receptacle 230.Naturally, the light absorbing material 216 would be placed at alocation on the inside surface 232 as dictated by the angle of the lightbeams L exiting the multi-fiber ferrule 212.

FIG. 13 illustrates two MTP connectors 300 prior to mating using aferrule with the offset axis from above. As is known in the art, MTPconnectors have an inner housing 302 as well as an outer housing 304. Inorder to use the present invention with the MTP connector 300, the innerhousing 302 will have a protruding portion 306 on one side and acorresponding recessed portion 308 on the other side. The protrudingportion 306 will have the light absorbing material 216 on an insidesurface to receive the light emitted from the multi-fiber ferrule in theMTP connector. Because the multi-fiber ferrules engage one another in amated condition, and the portion 306 must extend beyond the front ofmulti-fiber ferrule to catch the laser beams, there must be acorresponding recessed portion 308 to receive the protruding portion 306when mated.

FIG. 14 illustrates a multi-fiber ferrule 400 that has lenses 200,220 toimplement the offset axes of the optical fiber openings and the lenses.As with the embodiment in FIG. 7, the lenses 200 would be in the oddcolumns and the lenses 220 would be in the even columns (or vice-versa)so that only one multi-fiber ferrule would have to be manufactured toachieve the goal described herein. Since the lens axis is offset fromthe optical fiber openings, one of the two will have to be movedrelative to the other. It is easier to move (mold) the lenses in adifferent location than it is to move the optical fiber openings. Aswill be realized, the molding of the lenses in the front of themulti-fiber ferrule 400 is relatively simple as compared to moving thepins that form the optical fiber openings in the mold.

Applicant notes that the half of the lenses in the multi-fiber ferrule400 would cause the light exiting to go upwards and half of the lensescause the light to go downwards (to the top of the page in FIG. 14 andthe bottom of the page, respectively).

FIG. 15 illustrates the principles noted above with regard to thecollimated beams and the spacing at 70 mm from the front face of amulti-fiber ferrule. The circle 500 represents a 7 mm aperture(equivalent to the pupil of a human eye) and the 64 small circles 502represent the spacing of the light beams from the multi-fiber ferrule.As is clear, the collimated light beams from a highly collimatedmulti-fiber ferrule fit within the 7 mm aperture. Another option todirect the light out of the 7 mm aperture is to cause the light beams tobe radially distributed in a circular pattern that is larger than the 7mm aperture. In FIG. 16, the lenses 504 have been offset from theoptical fiber openings (or fiber axis) by about 3.6°. See FIG. 17 wherethe lens 504 with optical axis A-A is offset from the optical fiber axisB-B of optical fiber 116 to cause the light beam L to be directed at anangle of 3.6° from the optical axis A-A. This offset causes the lightbeams to be radially offset into a circle that has a 4.4 mm radius,which means that no more than about a quarter of the light beams 502would be able to be fit within the circle 500 at any one time. Toachieve a perfect circle as illustrated in FIG. 16, most of the lenseswould have a different angle (and thus offset between the lens and theoptical fiber openings). Naturally, the mating ferrules would have to bedesigned to receive the light and direct it to the ends of the opticalfibers.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the present inventionwithout departing from the spirit and scope of the invention. Thus it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1-11. (canceled)
 12. A mated pair arrangement of identical multi-fiberferrules, each multi-fiber ferrule having a front face to engage a frontface of a corresponding identical multi-fiber ferrule comprising: a mainbody having a front end, a back end, and a middle portion disposedbetween the front end and the back end, the front end having a frontface for mating with the other ferrule; a first opening on the back endof the main body configured to receive a plurality of optical fibers,each of the plurality of optical fibers being received in a respectivemicrohole inside the main body; and a plurality of lenses disposedadjacent the front end of the ferrule optically coupled to respectiveones of the plurality of optical fibers, the plurality of lenses beingrecessed into the front face; wherein a lens in one of the identicalmulti-fiber ferrule mates to a lens of a different prescription in theother identical multi-fiber ferrule.
 13. The mated pair arrangementaccording to claim 12, wherein the plurality of lenses is disposedadjacent the front end in at least one row and a plurality of columns,wherein the columns of lenses comprise a first plurality of columns anda second plurality of columns, the lenses in the first plurality ofcolumns have a first prescription and the lenses in the second pluralityof columns having a second prescription.
 14. The mated pair arrangementaccording to claim 13, wherein one of plurality of columns has aprescription comprising a flat prescription and the other of theplurality of columns has a convex prescription.
 15. The mated pairarrangement according to claim 13, wherein one of plurality of columnshas a concave prescription and the other of the plurality of columns hasa convex prescription.
 16. The mated pair arrangement according to claim12, wherein the plurality of lenses are centered in the front end of theunitary main body.
 17. The mated pair arrangement according to claim 12,wherein front face of the identical multi-fiber ferrule makes contactwith the front face of the other identical multi-fiber ferrulle.
 18. Amulti-fiber ferrule comprising: a main body having a front end, a backend, and a middle portion disposed between the front end and back end; afirst opening adjacent the back end of the unitary main body, the firstopening configured to receive at least two optical fibers; a pluralityof optical fiber openings extending from the first opening toward thefront end, each of the plurality of optical fiber openings configured toreceive an optical fiber; and a plurality of lenses disposed adjacentthe front end in at least one rows and a plurality of columns, each ofthe plurality of lenses being in optical alignment with a respective oneof the optical fiber openings, the lenses in each column having adifferent prescription from the lenses in each adjacent column.
 19. Themulti-fiber ferrule according to claim 18, wherein the columns of lensescomprise a first plurality of columns and a second plurality of columns,the lenses in the first plurality of columns have a first prescriptionand the lenses in the second plurality of columns having a secondprescription.
 20. The multi-fiber ferrule according to claim 19, whereinone of plurality of columns has a prescription comprising a flatprescription and the other of the plurality of columns has a convexprescription.
 21. The multi-fiber ferrule according to claim 19, whereinone of plurality of columns has a concave prescription and the other ofthe plurality of columns has a convex prescription.